'Optimal Shelterbelts / Windbreaks, OSB, contains 325 trees per 100 metres length. The cost is £1.18 per tree , plus delivery and VAT.  This will contain 18 trees 40/60cm (bare root) between October / March of each of these trees - Hornbeam, Black Poplar, Scots Pine, Grey Alder, Common Alder, Aspen, Rowan, Goat Willow, Field Maple, Silver Birch, Crab Apple, Bird Cherry, Guelder Rose, Hawthorn, Alder Buckthorn, Common Buckthorn, Hazel and Spindleberry.' "Measure the running metre length of the Shelter and x metre by 3.25 to arrive at total number of trees required" For more information, click on the link below ;- The Shelterbelt Initiative - Tree Nursery UK (tree-shop.co.uk)